Validity and reliability

The results of the subjective and objective evaluations on the 648 subjects were assessed and observed. Although these scores may appear to be similar, each child‟s level of development was different and specific for each individual. The manner of learning and attaining knowledge is different from child to child. Reliability and validity are essential in scientific research, as they „help to ensure that our measures are objective’ (Pellegrini et al., 2004: p140).

6.4.13.1 Validity

Instrument validity refers to the consistency of measurements and to the results on different occasions (McMillan et al., 2006: p130). Validity usually refers to the reliability and truthfulness of the measurements (Pellegrini et al., 2004: p140). The pre-tests and the post- tests are the same; so no deviation took place in the instrument used to assess the learners. The assessors tested all the subjects in a similar manner, in their mother tongue, and in groups of four children to one assessor. This was intended to ensure a fair standard of assessment. The two aspects focused on consisted of content validity and face validity.

Face validity ensures that the concepts tested all follow a developmental pattern and structure – for example, if a child cannot count from 1-5, s/he would therefore not be able to count by one-to-one correspondence 6-10 objects.

Content validity ensures that after a thorough investigation of the literature on the cognitive concepts, including the sub-sections on physical-motor, language and speech, socio- emotional, play and cognitive, that all the relevant aspects of the sub-sections were taken into

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account in the study. Tests devised and programmes implemented for the intervention were all based on the theory discussed in the conceptual framework.

i.) Internal validity

Internal validity is the degree to which conclusions and assumptions on the cause-and-effect relationships arising from an experiment are accurate and correct. There are many types of threats, which could affect the internal validity of a research design (McMillan et al., 2006: p134, 260). According to Polgar and Thomas (http://www.qmu.ac.uk/psych/RTrek/study _notes/web/sn3.htm, 18/03/09), „Internal validity concerns the soundness of an investigation‟. Possible threats, which may affect the internal validity of this trial, include the following:

 History

The history refers to various possible incidents that could occur outside or inside the context of the study. These incidents are out of the researcher‟s control; but they could influence the results of the study (McMillan et al., 2006: p136, p261).

There is a possibility that incidents outside the researcher‟s control might occur. The effectiveness of the intervention programme relies heavily on the children‟s school attendance. Children in the experimental group that are not at school on a regular basis may tend to have less effective results than those who are at school more consistently. Other external factors, which could have an impact on the children‟s development, or the lack thereof, would include: nutrition, family input, sleep patterns, abuse and neglect, health, and – of course, love.

According to Tebes (Ed. Jason & Glenwick, 2012, p23), it is important that researchers be sensitive to multiple cultural contexts. These would include: gender, race, ethnicity, age, sexual orientation, religion, disability status, or any number of individual contexts signifying human diversity.

 Instrumentation

Instrumentation refers to a visible change in the results. This is because of changes in the instrument itself, or changes in the person who is implementing the research (Neuman, 2006: p262; McMillan et al., 2006: p262).

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The instrument used for the pre-tests and the post-tests remained the same. The same scoring sheet was used for all the children, and the person implementing the research also remained unchanged throughout the research process; so no deviation took place.

 Subject attrition

There is frequently a difference in the number of subjects present for the pre-test, compared with those in the post-test (McMillan et al., 2006: p138). Only subjects present for both the pre-test and the post-test were submitted and analysed. As a result, the research study began with 800 participants; but only 648 were included in the study.

 Maturation

Maturation refers to changes in the individual subject that take place between the pre-test and the post-test. Children are constantly changing and growing. From one month to the next, they also become more mature. Factors, such as the time of day, the weather, the child‟s health, and even their moods would all affect their results in the tests (McMillan et al., 2006: p138-139, 261; Neuman, 2006: p261). The children used in this study were living in poverty- stricken areas; and as a result, many external factors could play a role in impacting pre- and post-test scores. These would include, but would not necessarily be limited to: nutrition, health, prior intervention, family input, sleep patterns, abuse and neglect, parental input, in addition to the resources available.

Maturation refers to changes in the individual subjects between their pre-test and their post- test scores. Because all children are constantly changing and growing, the fact that children develop would be a common occurrence in all the children, and one which cannot be prevented. Every precaution was taken to ensure that factors, such as the time of day, the weather, and the child‟s health would be considered when implementing the research.

6.4.13.2 External validity  Population external validity

Population external validity is the extent to which the results can be generalised to all other people: not only to people with similar characteristics. The results of a study should only be generalised when the population has similar characteristics to those of the subject group. These characteristics would include features, such as age, race, sex, ability, and socio-

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economic classification (McMillan et al., 2006: p141;

http://www.gifted.uconn.edu/siegle/research/ Samples/externalvalidity.html, 10/11/09). All the children – in both the experimental and the control groups – were between the ages of five and six-and-a-half years old. They attend one of 30 early-childhood centres in Port Elizabeth; they all come from a similar socio-economic sector; and they all speak the same mother-tongue, isiXhosa.

The racial breakdown of the practitioners includes all 30 practitioners being black females. The participants in this study were boys and girls, between the ages of five and six-and-a-half years old. All 648 subjects were isiXhosa speaking, and live in poverty-stricken environments in Port Elizabeth, South Africa.

6.4.13.3 Reliability

Reliability refers to the consistency of the uniformity in an experiment. It suggests that the same thing can be reproduced by different researchers under similar conditions, and they would all reach the same results (McMillan et al., 2006: p130, p188 & p198;

http://www.socialresearchmethods .net/kb/reliable.php, 3/11/09).

In order to determine whether the tests would be reliable, the tests were implemented by the same assessors, over a period of 6 weeks. The tests were administered in the children‟s mother tongue, isiXhosa, using the same instruments and resources for all the children.